Estimated storage of amorphous silica in soils of the circum‐Arctic tundra region. Issue 3 (15th March 2016)

• Record Type: Journal Article
• Authors: Alfredsson, H.; Clymans, W.; Hugelius, G.; Kuhry, P.; Conley, D. J.
• Is Part Of: Global biogeochemical cycles. Volume 30:Issue 3(2016:Mar.)
• Page Start: 479
• Page End: 500
• Publication Date: 2016-03-15
• Subjects: amorphous Si storage -- circum‐Arctic tundra -- landscape distribution -- permafrost -- upscaling -- wetland; Biogeochemical cycles -- Periodicals; Electronic journals; 577.1405
• DOI: 10.1002/2015GB005344
• Languages: English
• ISSNs: 0886-6236

Abstract

Abstract: We investigated the vertical distribution, storage, landscape partitioning, and spatial variability of soil amorphous silica (ASi) at four different sites underlain by continuous permafrost and representative of mountainous and lowland tundra, in the circum‐Arctic region. Based on a larger set of data, we present the first estimate of the ASi soil reservoir (0–1 m depth) in circum‐Arctic tundra terrain. At all sites, the vertical distribution of ASi concentrations followed the pattern of either (1) declining concentrations with depth (most common) or (2) increasing/maximum concentrations with depth. Our results suggest that a set of processes, including biological control, solifluction and other slope processes, cryoturbation, and formation of inorganic precipitates influence vertical distributions of ASi in permafrost terrain, with the capacity to retain stored ASi on millennial timescales. At the four study sites, areal ASi storage (0–1 m) is generally higher in graminoid tundra compared to wetlands. Our circum‐Arctic upscaling estimates, based on both vegetation and soil classification separately, suggest a storage amounting to 219 ± 28 and 274 ± 33 Tmol Si, respectively, of which at least 30% is stored in permafrost. This estimate would account for about 3% of the global soil ASi storage while occupying an equal portion of the global land area. This result does not support the hypothesis that the circum‐Arctic tundra soil ASi reservoir contains relatively higher amounts of ASi than other biomes globally as demonstrated for carbon. Nevertheless, climate warming has the potential to significantly alter ASi storage and terrestrial Si cycling in the Arctic. Key Points: The Arctic stores ~ 3% of the global soil amorphous Si (ASi) storage Thirty percent of the ASi is stored in permafrost ASi is currently stored on millennial timescales in the Arctic